The Experts below are selected from a list of 21504 Experts worldwide ranked by ideXlab platform
Sneha Kumar Kasera - One of the best experts on this subject based on the ideXlab platform.
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on fast and accurate detection of unauthorized wireless access points using clock skews
IEEE Transactions on Mobile Computing, 2010Co-Authors: Suman Jana, Sneha Kumar KaseraAbstract:We explore the use of clock skew of a wireless local area network access point (AP) as its fingerprint to detect unauthorized APs quickly and accurately. The main goal behind using clock skews is to overcome one of the major limitations of existing solutions - the inability to effectively detect Medium Access Control (MAC) address spoofing. We calculate the clock skew of an AP from the IEEE 802.11 Time Synchronization Function (TSF) time stamps sent out in the beacon/probe response frames. We use two different methods for this purpose - one based on linear programming and the other based on least-square fit. We supplement these methods with a heuristic for differentiating original packets from those sent by the fake APs. We collect TSF time stamp data from several APs in three different residential settings. Using our measurement data as well as data obtained from a large conference setting, we find that clock skews remain consistent over time for the same AP but vary significantly across APs. Furthermore, we improve the resolution of received time stamp of the frames and show that with this enhancement, our methodology can find clock skews very quickly, using 50-100 packets in most of the cases. We also discuss and quantify the impact of various external factors including temperature variation, virtualization, clock source selection, and NTP Synchronization on clock skews. Our results indicate that the use of clock skews appears to be an efficient and robust method for detecting fake APs in wireless local area networks.
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on fast and accurate detection of unauthorized wireless access points using clock skews
ACM IEEE International Conference on Mobile Computing and Networking, 2008Co-Authors: Suman Jana, Sneha Kumar KaseraAbstract:We explore the use of clock skew of a wireless local area network access point (AP) as its fingerprint to detect unauthorized APs quickly and accurately. The main goal behind using clock skews is to overcome one of the major limitations of existing solutions - the inability to effectively detect Medium Access Control (MAC) address spoofing. We calculate the clock skew of an AP from the IEEE 802.11 Time Synchronization Function (TSF) timestamps sent out in the beacon/probe response frames. We use two different methods for this purpose - one based on linear programming and the other based on least square fit. We supplement these methods with a heuristic for differentiating original packets from those sent by the fake APs. We collect TSF timestamp data from several APs in two different residential settings. Using our measurement data as well as data obtained from a large conference setting, we find that clock skews remain consistent over time for the same AP but vary significantly across APs. Furthermore, we improve the resolution of received timestamp of the frames and show that with this enhancement our methodology can find clock skews very quickly, using 50-100 packets in most of the cases. We also discuss and quantify the impact of various external factors including temperature variation, virtualization, and NTP Synchronization on clock skews. Our results indicate that the use of clock skews appears to be an efficient and robust method for detecting fake APs in wireless local area networks.
Suman Jana - One of the best experts on this subject based on the ideXlab platform.
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on fast and accurate detection of unauthorized wireless access points using clock skews
IEEE Transactions on Mobile Computing, 2010Co-Authors: Suman Jana, Sneha Kumar KaseraAbstract:We explore the use of clock skew of a wireless local area network access point (AP) as its fingerprint to detect unauthorized APs quickly and accurately. The main goal behind using clock skews is to overcome one of the major limitations of existing solutions - the inability to effectively detect Medium Access Control (MAC) address spoofing. We calculate the clock skew of an AP from the IEEE 802.11 Time Synchronization Function (TSF) time stamps sent out in the beacon/probe response frames. We use two different methods for this purpose - one based on linear programming and the other based on least-square fit. We supplement these methods with a heuristic for differentiating original packets from those sent by the fake APs. We collect TSF time stamp data from several APs in three different residential settings. Using our measurement data as well as data obtained from a large conference setting, we find that clock skews remain consistent over time for the same AP but vary significantly across APs. Furthermore, we improve the resolution of received time stamp of the frames and show that with this enhancement, our methodology can find clock skews very quickly, using 50-100 packets in most of the cases. We also discuss and quantify the impact of various external factors including temperature variation, virtualization, clock source selection, and NTP Synchronization on clock skews. Our results indicate that the use of clock skews appears to be an efficient and robust method for detecting fake APs in wireless local area networks.
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on fast and accurate detection of unauthorized wireless access points using clock skews
ACM IEEE International Conference on Mobile Computing and Networking, 2008Co-Authors: Suman Jana, Sneha Kumar KaseraAbstract:We explore the use of clock skew of a wireless local area network access point (AP) as its fingerprint to detect unauthorized APs quickly and accurately. The main goal behind using clock skews is to overcome one of the major limitations of existing solutions - the inability to effectively detect Medium Access Control (MAC) address spoofing. We calculate the clock skew of an AP from the IEEE 802.11 Time Synchronization Function (TSF) timestamps sent out in the beacon/probe response frames. We use two different methods for this purpose - one based on linear programming and the other based on least square fit. We supplement these methods with a heuristic for differentiating original packets from those sent by the fake APs. We collect TSF timestamp data from several APs in two different residential settings. Using our measurement data as well as data obtained from a large conference setting, we find that clock skews remain consistent over time for the same AP but vary significantly across APs. Furthermore, we improve the resolution of received timestamp of the frames and show that with this enhancement our methodology can find clock skews very quickly, using 50-100 packets in most of the cases. We also discuss and quantify the impact of various external factors including temperature variation, virtualization, and NTP Synchronization on clock skews. Our results indicate that the use of clock skews appears to be an efficient and robust method for detecting fake APs in wireless local area networks.
Huang Wei - One of the best experts on this subject based on the ideXlab platform.
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application of ieee1588 time Synchronization in digital substation
Power System Protection and Control, 2010Co-Authors: Huang WeiAbstract:This paper introduces the application of time Synchronization schemes in digital substation and compares the technical characteristics of these schemes. Then for the high accuracy Synchronization requirement of IEC61850 based digital substation, a time Synchronization system based on IEEE1588 which can support sub-microsecond level of accuracy is put forward and the theory of IEEE1588 is expatiated. Based on IEEE1588, t wo application schemes on time Synchronization network in substation are expounded. One is based on boundary clock and the other is based on transparent clock.The advantage of the scheme based on transparent clock is discussed. At last this paper presents a design scheme of the time Synchronization device ,a nd analyzes the important factors which impact the IEEE1588 time Synchronization Function, as well as the compensation methods.
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application of ieee1588 time Synchronization in digital substation
Power System Protection and Control, 2010Co-Authors: Huang WeiAbstract:This paper introduces the application of time Synchronization schemes in digital substation and compares the technical characteristics of these schemes. Then for the high accuracy Synchronization requirement of IEC61850 based digital substation, a time Synchronization system based on IEEE1588 which can support sub-microsecond level of accuracy is put forward and the theory of IEEE1588 is expatiated. Based on IEEE1588, t wo application schemes on time Synchronization network in substation are expounded. One is based on boundary clock and the other is based on transparent clock.The advantage of the scheme based on transparent clock is discussed. At last this paper presents a design scheme of the time Synchronization device ,a nd analyzes the important factors which impact the IEEE1588 time Synchronization Function, as well as the compensation methods.
Thomas Kunz - One of the best experts on this subject based on the ideXlab platform.
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a clock sampling mutual network time Synchronization algorithm for wireless ad hoc networks
Wireless Communications and Networking Conference, 2005Co-Authors: C H Rentel, Thomas KunzAbstract:In this paper, we propose the clock-sampling mutual network Synchronization (CSMNS) as a non-hierarchical and mutual network Synchronization algorithm for wireless ad hoc networks. CSMNS shows superior performance to the IEEE 802.11 timing Synchronization Function in terms of accuracy, scalability and robustness. An overall view of the differences between the two approaches is presented. CSMNS is compatible with the beacon messages used in the IEEE 802.11 standard, and it is PHY transparent. CSMNS-RMN (rotating master node) is proposed in order to further reduce beacon collisions and overhead. Stability, is a factor that must be considered in CSMNS. However, values of the proportional gain below 0.3 suggest a good stability performance. The use of larger C/sup max/ values in more dense networks and/or the use of techniques that randomly prioritize the transmission of beacons can further reduce the overhead and risks of instability.
C H Rentel - One of the best experts on this subject based on the ideXlab platform.
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a clock sampling mutual network time Synchronization algorithm for wireless ad hoc networks
Wireless Communications and Networking Conference, 2005Co-Authors: C H Rentel, Thomas KunzAbstract:In this paper, we propose the clock-sampling mutual network Synchronization (CSMNS) as a non-hierarchical and mutual network Synchronization algorithm for wireless ad hoc networks. CSMNS shows superior performance to the IEEE 802.11 timing Synchronization Function in terms of accuracy, scalability and robustness. An overall view of the differences between the two approaches is presented. CSMNS is compatible with the beacon messages used in the IEEE 802.11 standard, and it is PHY transparent. CSMNS-RMN (rotating master node) is proposed in order to further reduce beacon collisions and overhead. Stability, is a factor that must be considered in CSMNS. However, values of the proportional gain below 0.3 suggest a good stability performance. The use of larger C/sup max/ values in more dense networks and/or the use of techniques that randomly prioritize the transmission of beacons can further reduce the overhead and risks of instability.
